What do deer eat? It would almost be easier to answer the question “What don’t deer eat?” Deer, especially whitetails, can survive on a diverse menu that includes agricultural crops, wild native flora, and non-native plants that suburbanites plant in their gardens and flowerbeds. Also, deer eat a lot. Depending on the time of year, a whitetail needs to eat eight percent of its body weight in leafy greens and browse every day to stay healthy.